C# Extension method that generates a list of exception messages from the top level down through all inner exceptions

ExceptionMessages.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace System {

    public static partial class ExceptionExtensions {

        /// <summary>
        /// Returns a list of all the exception messages from the top-level
        /// exception down through all the inner exceptions. Useful for making
        /// logs and error pages easier to read when dealing with exceptions.
        /// Usage: Exception.Messages()
        /// </summary>
        public static IEnumerable<string> Messages( this Exception ex ) {
            // return an empty sequence if the provided exception is null
            if (ex == null) { yield break; }
            // first return THIS exception's message at the beginning of the list
            yield return ex.Message;
            // then get all the lower-level exception messages recursively (if any)
            IEnumerable<Exception> innerExceptions = Enumerable.Empty<Exception>();

            if (ex is AggregateException && (ex as AggregateException).InnerExceptions.Any())
            {
                innerExceptions = (ex as AggregateException).InnerExceptions;
            }
            else if (ex.InnerException != null)
            {
                innerExceptions = new Exception[] { ex.InnerException };
            }

            foreach (var innerEx in innerExceptions)
            {
                foreach (string msg in innerEx.Messages())
                {
                    yield return msg;
                }
            }
        }

    }
}

What's about Exception.GetBaseException() ? https://stackoverflow.com/questions/2085196/proper-way-to-find-the-innermost-exception